Pulmonary hypertension is high blood pressure in the arteries, capillaries and veins within the lungs. This condition is different from hypertension, or high blood pressure, measured by a traditional test with a cuff around your arm. Pulmonary hypertension causes the right side of the heart to work harder due to higher pressures. This increased pressure may be detected by heart sounds heard via a stethoscope or bulging neck veins. Warning signs for pulmonary hypertension include fatigue, dizziness and shortness of breath.